Duke Energy is banking on a bad deal for Indiana utility customers. The energy giant is spending billions more than expected on a massive new coal plant in Edwardsport, Indiana, that will release four million tons of carbon dioxide every year.

The strikes against the Duke coal plant are significant. The 618-megawatt plant, which was put online in June of 2013, is projected to emit four million tons of carbon dioxide every year for at least the next 30 years. The facility will cost more than $3 billion dollars—nearly two billion more than initial estimates—the bulk of which Duke aims to impose on Indiana ratepayers. And these current estimates do not include compliance costs associated with reducing carbon dioxide, despite the fact that President Obama announced in June 2013 that his administration would complete these climate change regulations within the next two years.

Earthjustice filed an amicus (“friend of the court”) brief to support efforts that challenge the plant’s approval. The amicus brief identifies a path forward for Duke to protect Indiana ratepayers: Duke must diversify its portfolio to replace coal with clean energy that is becoming increasingly cost-effective, especially when climate impacts are taken into account.